throttle tension

[RonSass]

I have a 90hp 4stroke yahama center console throttle. The throttle is too loose. Where do you tighten it? I have looked with no luck.

[boats.net]

There is a throttle friction screw on control box, 703 side mount box has friction screw in front of box, 704 binnacle control box friction screw is under plastic cover(screw is located on rear at bottom of control box).